In some treatments, patients need to be administered medicaments from an applicator by a health care provider, sometimes at home. The amount of medicament required to be administered to a patient, depends upon factors such as, the size and weight of the patient, the age and sex of the patient, the patient age group, i.e., whether the patient is a child or an adult, and the like.
In order to administer the proper dose to a patient, applicators are required to be metered to deliver a desired dose volume of the medicament from the entire dose volume. Alternatively, the health care provider needs to adjust the dose volume to be delivered.
Presently available options have certain drawbacks. In accordance with one available embodiment, several versions of the applicator device are manufactured, with each version having a different volume of the medicament. For each dose a different version of the device is used. This requires the distributor of the device and the pharmacist to use up a relatively large shelf space for maintaining the inventory of multiple versions of the device containing different amounts of the drug.
In accordance with another available option, where variable doses can be set, a health care provider, who is less educated in the field, is apt to make an error in setting the proper dosage. This can result in disastrous results and even lead to a medical emergency.
U.S. Pat. No. 7,329,241 relates to a drug delivery system for administering an adjustable preset dose of a drug such as diazepam to a patient. This device is available in the U.S. market under the trade name Diastat Acudial. The patent suggests an apparatus for dispensing a dose of a drug in a syringe having a plunger, comprising an outer housing and an inner housing adapted for encircling the syringe, such that the inner housing is positioned within the outer housing to set the dose of the drug and a locking assembly. This patent further envisages a dosage indicator disposed on the inner housing and a window for viewing the dosage indicator on the outer housing. Also is suggested, a locking assembly connected to the inner housing and the outer housing for fixing the relative positions of the inner housing and the outer housing such that the dosage indicator is viewable through the opening in the outer housing.
U.S. Patent Application No. 20100305515 (“the '515 application”) discloses a drug delivery system for administering an adjustable preset dose of a drug or a nutritional supplement to a human or veterinary patient or for delivering, for example, fertilizer in agricultural use. The '515 application relates to an apparatus for dispensing a dose of a drug in a syringe having a plunger with multiple flanges, and locking assembly. Also, the suggested syringe is bulky and has complex and delicate moving parts which can be difficult to assemble and expensive to manufacture.
Thus there is still a need for a syringe device with which an accurate amount a liquid can be discharged through a simple operation which avoids the above disadvantages. In particular, syringe device should comprise relatively few and simple parts, should not require excessive amounts of space, should be robust and at the same time should provide reliable fluid discharge.